The present invention relates to a gaming machine. The invention has been developed primarily for use as an electronic gaming machine and will be described hereinafter by reference to this application. However, it will be appreciated that the invention may also be implemented for any type of gaming machine, including a mechanical or electro-mechanical gaming machine.
The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its advantages to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should not be construed as an express or implied admission that such art is widely known or forms part of common general knowledge in the field.
Conventional gaming machines typically involve awarding prizes to a player according to predetermined combinations of game symbols that appear on an array of game squares displayed on a screen, typically organised into three rows and five columns (a 5×3 array). Other arrays, such as a 3×3 or 4×3, may be used. Each gaming machine randomly selects the game symbols that appear on the array, each column of the array being a “reel”.
One type of gaming machine comprises a mechanical or electro-mechanical device, where a motor rotates a plurality of annular rings or drums that form reels. Each reel has a reel strip that displays game symbols in preset game symbol positions. A frame covers the rings to provide a window through which only a subset of game symbol positions (and hence game symbols) were visible to the player. Thus, for a game using a 5×3 array, the window would only permit three rows of five rings to be visible to create the game array. An internal game controller within the gaming machine controls operation of the motor and hence rotation of the reels. Thus, by controlling when each reel starts and stops in its respective rotation, the game controller controls the display of the game symbols in the window. Sensors linked to the reels indicate which game symbols are displayed in the window and communicate with the game controller so that the game controller is able to award prizes based on winning combinations of game symbols displayed on the reels in the window. The game controller typically comprises one or more electric circuits for controlling various functions of the gaming machine, such as the above mentioned control of the motor, communicating with the sensors, verifying that the correct amount of a bet has been made via one or more value receiving mechanisms to enable operation of the motors, controlling any visual and/or audio effects associated with operation of the gaming machine and controlling operation of various alarms to alert any tampering with the gaming machine.
Another type of gaming machine, known as an electronic gaming machine or EGM, replaces the mechanical reels and motor with a video display screen on which video images of the reels are displayed. The EGM has an internal electronic game controller, typically a computer, that controls the display of images on the video display screen so that the reels are visibly spun on the screen to simulate a physical reel of a traditional gaming machine. EGMs tend to be more versatile in providing game information, varying the probabilities for a player to win a prize and varying the type of game that is played.
Bonus or “feature” games may also be provided by a gaming machine in addition to a base or main game. Typically feature games use the same set of reels as the main game and are limited to a set of free games operated under a single set of rules. This means that the feature game is restricted by the same set of rules, and so there is no variation in the play of the feature game.
Also, gaming machines can offer one or more bonus prizes to the player during play of the game. The most common type of bonus prize that is awarded by the gaming machine is a jackpot prize, the main example of which is a progressive jackpot prize. However, in order to provide multiple jackpot or bonus prizes, the gaming machine has to reduce the “return to player” or RTP for the base game and any feature games to compensate for the RTP of each bonus prize that is offered. This standard structure to providing bonus prizes is inefficient as not all the bonus prizes may be available for every game played on the gaming machine. For example, some bonus prizes only available if the player bets a threshold amount. Also, where more than one game is offered to play on the same electronic gaming machine some bonus prizes are tied to a particular game or set of games and not all the games offered on the gaming machine. This inefficiency limits the operation of the gaming machine, irrespective of whether it is a mechanical, electro-mechanical or electronic gaming machine.
It is an object of the present invention to overcome or substantially ameliorate one or more of the disadvantages of prior art, or at least to provide a useful alternative.